1. Field of the Invention
The present invention relates to a fuel injection control apparatus which is arranged in a fuel supply system of a spark ignition type engine and electronically controls a fuel injection amount on the basis of an engine temperature.
2. Description of the Related Art
In a fuel supply system of a spark ignition type engine, in order to secure a stable rotation from a cold start of the engine to a warm-up finish, it is general to compensate so as to increase a fuel injection amount in correspondence to an engine temperature. In other words, for example, in a fuel injection control apparatus described in Japanese Unexamined Patent Publication No. 5-1588 and Japanese Unexamined Patent Publication No. 6-117316 and shown in FIG. 3, a control unit 20 determines a warm-up progress state of an engine 1 on the basis of an engine temperature detected by a water temperature sensor 11, an oil temperature sensor 12 and the like provided in the engine 1 so as to adjust a fuel injection amount of a fuel injection valve 21 in such a manner as to increase in comparison with a warm time.
However, since the water temperature sensor 11 and the oil temperature sensor 12 are directly attached to the engine 1, a protecting means such as a water proofing or the like is necessary, and since the control unit 20 is normally arranged at a position apart from the engine 1, a wiring connected to the water temperature sensor 11 and the oil temperature sensor 12 is necessary, and an output portion for outputting a signal is necessary in the sensor. Accordingly, the sensor itself becomes expensive, and an entire cost of the system tends to be expensive.
The present invention intends to solve the problem as mentioned above, and an object of the present invention is to provide a fuel injection control apparatus of an engine in which a sensor for detecting an engine temperature is inexpensive and a wiring to a control unit is made unnecessary, thereby restricting a system cost low.